The present invention relates to novel heterocyclic compounds and to their formulation and use as pharmaceuticals.
The modes of action of phosphodiesterases and also tumour necrosis factors (TNF), and the therapeutic utilities of inhibitors thereof, are described in WO-A-97/44036 and U.S. Pat. No. 5,804,588, the contents of which are incorporated herein by reference. WO-A-98/22460 and U.S. patent application Ser. No. 09/422,473, filed Nov. 17, 1997, disclose benzoxazoles that also have such activity.
This invention provides novel compounds having therapeutic utility, in particular for the treatment of disease states associated with proteins which mediate cellular activity, for example by inhibiting TNF and/or PDE IV. According to the invention, the compounds are of formula (i): 
wherein
R1 is C1-3 alkyl optionally substituted with one or more fluorines;
R2 is C1-6 alkyl, cycloalkyl or NR4R5;
R3 is a pyrazole, imidazole or isoxazole group of partial formula (A), (B) or (C) 
NR4R5 is a nitrogen-containing heterocyclic ring, such as morpholine, pyrrolidine, piperidine or azetidine;
R6 is C1-3 alkyl, and
R7 and R8, which are the same or different, each represents C1-3 alkyl, halogen, CF3 or CN;
or a pharmaceutically-acceptable salt thereof.
In summary, the compounds of the invention represent a selection within the scope of WO-A-98/22460. The novel compounds have superior pK, and therefore enhanced bioavailability.
This invention provides also a method for mediating or inhibiting the enzymatic activity or catalytic activity of PDE IV in a mammal in need thereof and for inhibiting the production of TNF in a mammal in need thereof, which comprises administering to said mammal an effective amount of a compound of Formula (i) or a pharmaceutically-acceptable salt thereof.
The term xe2x80x9cC1-6 alkylxe2x80x9d means a straight or branched chain alkyl moiety having one to six carbon atoms, including, for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl and the like. The term xe2x80x9cC1-3 alkylxe2x80x9d means methyl, ethyl, propyl or isopropyl.
One group of compounds of the invention is of formula (i) in which R1 is CH3 or CHF2.
Another group of compounds of the invention is of formula (i) in which R2 is ethyl, cyclopropyl or NR4R5.
In one particular group of compounds of the invention R3 is a pyrazole group in which R6 is in particular CH3 or C2H5 and R7 is especially CN, Cl, CH3, C2H5, Br or CF3. Especially preferred is where R6 is in particular CH3 and R7 is especially CN, CH3, or CF3.
R3 in another group of compounds of formula (i) is an imidazole group in which R6 is in particular CH3 or C2H5 and R7 is particularly CN or CH3.
A further group of compounds of the invention is where R3 is an isoxazole group in which R7 is in particular CH3, CF3, C2H5 or CN and R8 is especially CH3, CF3, C2H5 or CN. Especially preferred is where R7 is in particular CH3, CF3, or CN and R8, is especially CH3, CF3, or CN.
Certain of the compounds of formula (i) which contain a basic group form acid addition salts. Suitable acid addition salts include pharmaceutically-acceptable inorganic salts such as the sulphate, nitrate, phosphate, borate, hydrochloride and hydrobromide, and pharmaceutically-acceptable organic acid addition salts such as acetate, tartrate, maleate, citrate, succinate, benzoate, ascorbate, methanesulphate, xcex1-ketoglutarate, xcex1-glycerophosphate and glucose-1-phosphate. The pharmaceutically-acceptable salts of the compounds of formula (i) are prepared using conventional procedures.
Compounds of the invention may be prepared from suitable carboxylic acids (ii) and amines (iii), as described in WO-A-98/22460 
Carboxylic acids of formula (ii) are prepared using standard conditions known to those skilled in the art such as carboxylation of bromides of formula (iv) or (vi) using carbon monoxide gas and an organopalladium catalyst. Amines of formula (iii) are either commercially available, previously described compounds, or are prepared using standard conditions known to those skilled in the art.
Bromides of formula (vi) are either previously described or prepared using standard conditions known to those skilled in the art. For example, compounds of formula (vi) in which R1 represents methyl and R2 represents NR4R5 are conveniently prepared from 4-methoxy-2-sulfanylmethylbenzooxazole by displacement of the 2-methylsulfanyl group on heating with the appropriate amine HNR4R5. 
Compounds in which R1 represents difluoromethyl by be prepared from intermediates in which R1 represents methyl by demethylation followed by difluoromethylation. Demethylation of compounds of formula (vi) may be carried out under standard conditions known to those skilled in the art, for example by using ethane thiol and sodium hydride in dimethylformamide at elevated temperature, or with boron tribromide in dichloromethane. Difluoromethylation of the phenols (v) may be achieved using any suitable conditions known to those skilled in the art, for example by passing chlorodifluoromethane gas through a solution of the appropriate phenol in a mixture of aqueous sodium hydroxide and dioxane at elevated temperature to give compounds of formula (iv) 
The invention includes the prevention and treatment of TNF-mediated disease or disease states, by which is meant any and all disease states in which TNF plays a role, either by production of TNF itself, or by TNF causing another cytokine to be released, such as but not limited to IL-1 or IL-6. A disease state in which IL-1, for instance, is a major component, and whose production or action is exacerbated or secreted in response to TNF, would therefore be considered a disease state mediated by TNF. As TNF-xcex2 (also known as lymphotoxin) has close structural homology with TNF-xcex1 (also known as cachectin), and since each induces similar biological responses and binds to the same cellular receptor, both TNF-xcex1 and TNF-xcex2 are inhibited by compounds of the present invention and thus are herein referred to collectively as xe2x80x9cTNFxe2x80x9d unless specifically delineated otherwise.
PDE IV inhibitors are useful in the treatment of a variety of allergic and inflammatory diseases, including: asthma, chronic bronchitis, atopic dermatitis, atopic eczema, urticaria, allergic rhinitis, allergic conjunctivitis, vernal conjunctivitis, inflammation of the eye, allergic responses in the eye, eosinophilic granuloma, psoriasis, Bechet""s disease, erythematosis, anaphylactoid purpura nephritis, joint inflammation, arthritis, rheumatoid arthritis and other arthritic conditions such as rheumatoid spondylitis and osteoarthritis, septic shock, ulcerative colitis, Crohn""s disease, reperfusion injury of the myocardium and brain, chronic glomerulonephritis, endotoxic shock and adult respiratory distress syndrome. In addition, PDE IV inhibitors are useful in the treatment of diabetes insipidus and conditions associated with cerebral metabolic inhibition, such as cerebral senility, senile dementia (Alzheimer""s disease), memory impairment associated with Parkinson""s disease, depression and multi-infarct dementia. PDE IV inhibitors are also useful in conditions ameliorated by neuroprotectant activity, such as cardiac arrest, stroke and intermittent claudication. Additionally, PDE IV inhibitors could have utility as gastroprotectants. A special embodiment of the therapeutic methods of the present invention is the treatment of asthma.
The viruses contemplated for treatment herein are those that produce TNF as a result of infection, or those which are sensitive to inhibition, such as by decreased replication, directly or indirectly, by the TNF inhibitors of Formula (i). Such viruses include, but are not limited to HIV-1, HIV-2 and HIV-3, cytomegalovirus (CMV), influenza, adenovirus and the Herpes group of viruses, such as, but not limited to, Herpes zoster and Herpes simplex.
This invention more specifically relates to a method of treating a mammal, afflicted with a human immunodeficiency virus (HIV), which comprises administering to such mammal an effective TNF inhibiting amount of a compound of Formula (i) or a pharmaceutically-acceptable salt thereof
The compounds of this invention may be also be used in association with the veterinary treatment of animals, other than humans, in need of inhibition of TNF production. TNF mediated diseases for treatment, therapeutically or prophylactically, in animals include disease states such as those noted above, but in particular viral infections. Examples of such viruses include, but are not limited to feline immunodeficiency virus (FIV) or other retroviral infection such as equine infectious anaemia virus, caprine arthritis virus, visna virus, maedi virus and other lentiviruses.
The compounds of this invention are also useful in treating parasite, yeast and fungal infections, where such yeast and fungi are sensitive to upregulation by TNF or will elicit TNF production in vivo. A preferred disease state for treatment is fungal meningitis.
The compounds of formula (i) are preferably in pharmaceutically-acceptable form. By pharmaceutically-acceptable form is meant, inter alia, a pharmaceutically-acceptable level of purity excluding normal pharmaceutical additives such as diluents and carriers, and including no material considered toxic at normal dosage levels. A pharmaceutically-acceptable level of purity will generally be at least 50% excluding normal pharmaceutical additives, preferably 75%, more preferably 90% and still more preferably 95%. When used herein the term xe2x80x9cpharmaceutically-acceptablexe2x80x9d encompasses materials suitable for both human and veterinary use.
A compound of formula (i) or where appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceutically-acceptable solvate thereof, may be administered per se or, preferably, as a pharmaceutical composition also comprising a pharmaceutically-acceptable carrier.
Accordingly, the present invention provides a pharmaceutical composition comprising a compound of formula (i) or where appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceutically-acceptable solvate thereof, and a pharmaceutically-acceptable carrier.
The active compound may be formulated for administration by any suitable route, the preferred route depending upon the disorder for which treatment is required, and is preferably in unit dosage form or in a form that a human patient may administer to himself in a single dosage. Advantageously, the composition is suitable for oral, rectal, topical, parenteral administration or through the respiratory tract. Preparations may be designed to give slow release of the active ingredient.
The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. In addition to the treatment of warm-blooded animals such as mice, rats, horses, cattle, sheep, dogs, cats, etc, the compounds of the invention are effective in the treatment of humans.
The compositions of the invention may be in the form of tablets, capsules, sachets, vials, powders, granules, lozenges, suppositories, reconstitutable powders, or liquid preparations such as oral or sterile parenteral solutions or suspensions. Topical formulations are also envisaged where appropriate.
In order to obtain consistency of administration it is preferred that a composition of the invention is in the form of a unit dose. Unit dose presentation forms for oral administration may be tablets and capsules and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers for example microcrystalline cellulose, lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting lubricants, for example magnesium stearate; disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycollate or microcrystalline cellulose; or pharmaceutically-acceptable wetting agents such as sodium lauryl sulphate.
Solid oral compositions may be prepared by conventional methods of blending, filling, tabletting or the like. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers.
Such operations are of course conventional in the art. The tablets may be coated according to methods well known in normal pharmaceutical practice, in particular with an enteric coating.
Oral liquid preparations may be in the form of, for example, emulsions, syrups or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, gelatin, hydroxyethylcellulose, carboxymethylcellulose, aluminium stearate gel, hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia, non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters such as esters of glycerine, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid; and if desired conventional flavouring or colouring agents.
Compositions may also suitably be presented for administration to the respiratory tract as a snuff or an aerosol or solution for a nebuliser, or as a microfine powder for insufflation, alone or in combination with an inert carrier such as lactose. In such a case the particles of active compound suitably have diameters of less than 50 xcexcm, such as from 0.1 to 50 xcexcm, preferably less than 10 xcexcm, for example from 1 to 10 xcexcm, 1 to 5 xcexcm or from 2 to 5 xcexcm. Where appropriate, small amounts of other anti-asthmatics and bronchodilators for example sympathomimetic amines such as isoprenaline, isoetharine, salbutamol, phenylephrine and ephedrine; corticosteroids such as prednisolone and adrenal stimulants such as ACTH may be included.
For parenteral administration, fluid unit dosage forms are prepared utilizing the compound and a sterile vehicle, and, depending on the concentration used, can be either suspended or dissolved in the vehicle. In preparing solutions, the compound can be dissolved in water for injection and filter-sterilised before filling into a suitable vial or ampoule and sealing.
Advantageously, adjuvants such as a local anaesthetic, a preservative and buffering agents can be dissolved in the vehicle. To enhance the stability, the composition can be frozen after filling into the vial and the water removed under vacuum. Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilisation cannot be accomplished by filtration. The compound can be sterilised by exposure to ethylene oxide before suspending in the sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound.
The compositions may contain from 0.1% to 99% by weight, preferably from 10-60% by weight, of the active material, depending on the method of administration.
Compounds of formula (i), or if appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceutically-acceptable solvate thereof, may also be administered as a topical formulation in combination with conventional topical excipients.
Topical formulations may be presented as, for instance, ointments, creams or lotions, impregnated dressings, gels, gel sticks, spray and aerosols, and may contain appropriate conventional additives such as preservatives, solvents to assist drug penetration and emollients in ointments and creams. The formulations may contain compatible conventional carriers, such as cream or ointment bases and ethanol or oleyl alcohol for lotions.
Suitable cream, lotion, gel, stick, ointment, spray or aerosol formulations that may be used for compounds of formula (i) or if appropriate a pharmaceutically-acceptable salt thereof, are conventional formulations well known in the art, for example, as described in standard text books such as Harry""s Cosmeticology published by Leonard Hill Books, Remington""s Pharmaceutical Sciences, and the British and US Pharmacopoeias.
Suitably, the compound of formula (i), or if appropriate a pharmaceutically-acceptable salt thereof, will compromise from about 0.5 to 20% by weight of the formulation, favourably from about 1 to 10%, for example 2 to 5%.
The dose of the compound used in the treatment of the invention will vary in the usual way with the seriousness of the disorders, the weight of the sufferer, and the relative efficacy of the compound. However, as a general guide suitable unit doses may be 0.1 to 1000 mg, such as 0.5 to 200, 0.5 to 100 or 0.5 to 10 mg, for example 0.5, 1, 2, 3, 4 or 5 mg; and such unit doses may be administered more than once a day, for example 2, 3, 4, 5 or 6 times a day, but preferably 1 or 2 times per day, so that the total daily dosage for a 70 kg adult is in the range of about 0.1 to 1000 mg, that is in the range of about 0.001 to 20 mg/kg/day, such as 0.007 to 3, 0.007 to 1.4, 0.007 to 0.14 or 0.01 to 0.5 mg/kg/day, for example 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1 or 0.2 mg/kg/day, and such therapy may extend for a number of weeks or months.
Assay Methods
The assays used to confirm the phosphodiesterase IV inhibitory activity of compounds of formula (I) are standard assay procedures as disclosed by Schilling et al, Anal. Biochem. 216:154 (1994), Thompson and Strada, Adv. Cycl. Nucl. Res. 8:119 (1979) and Gristwood and Owen, Br. J. Pharmacol. 87:91P (1986).
Compounds of formula (i) have exhibited activity at levels consistent with those believed to be useful in treating phosphodiesterase IV related disease states in those assays.
The ability of compounds of formula (i) to inhibit TNF production in human peripheral blood mononuclear cells (PMBC""s) is measured as follows. PMBC""s are prepared from freshly taken blood or xe2x80x9cBuffy coatsxe2x80x9d by standard procedures. Cells are plated out in RPMI1640+1% foetal calf serum in the presence and absence of inhibitors. LPS (Lipopolysaccharide (endotoxin); 100 ng/ml) is added and cultures are incubated for 22 h at 37xc2x0 C. in an atmosphere of 95% air/5% CO2. Supernatants are tested for TNFxcex1 by ELISA (Enzyme linked immunosorbent assay) using commercially available kits.
Activity in a guinea pig lung model is measured using the procedures described by Mauser et al, Am. Rev. Respir. Dis. 148:1623 (1993), and Am. J. Respir. Crit. Care Med. 152:467 (1995).
The compound of Example 7 of WO-A-98/22460 (see the assay described there) achieves Cmax 15 ng/ml when dosed orally at 5 mg/kg to guinea pigs. Example 1 herein (representative of the present invention) achieves Cmax=4370 ng/ml when dosed orally at 3 mg/kg to guinea pigs.